Understanding Dementia in Other Diseases, Without Behavioral Disturbance: ICD-10 Code F02.80

What This Code Means

ICD-10-CM code F02.80 is the standardized medical code for Dementia in Other Diseases Classified Elsewhere, Without Behavioral Disturbance. It applies when dementia is caused by another medical condition the patient already has — and that underlying disease is documented separately in the chart with its own ICD-10 code.

Common examples include dementia secondary to Parkinson's disease (G20), Huntington's disease (G10), HIV disease (B22), traumatic brain injury (S06), Creutzfeldt-Jakob disease (A81.0), and certain late-effect conditions. Per ICD-10-CM coding rules, F02.80 is never used alone — the underlying disease must also be coded on the same claim, and is typically listed first.

The trailing .80 specifies without behavioral disturbance. If symptoms like agitation, aggression, wandering, or psychosis are documented, the code becomes F02.81 instead. The behavioral specifier matters for care planning and can affect coverage of certain services.

Why Are There So Many Similar Codes?

You might wonder why one "dementia" code isn't enough. Dementia coding is layered for a reason — the underlying cause changes prognosis, treatment, and what kind of help a family should plan for. ICD-10 distinguishes between:

• Underlying cause: Alzheimer's (G30.x), vascular (F01.x), Lewy body (G31.83), frontotemporal (G31.0x), unspecified (F03.9x), and dementia secondary to other diseases (F02.x) each have their own codes
• Etiology pairing: F02.x specifically signals that another disease is driving the dementia, and that disease must be coded too — G20 for Parkinson's, G10 for Huntington's, B22 for HIV, S06 for TBI, and so on
• Behavioral disturbance: The fifth digit distinguishes "without" (.80) from "with" (.81), since behavioral symptoms drive a large share of family burden and service needs
• Stage and severity: Newer ICD-10-CM updates add severity specifiers (mild, moderate, severe) that some clinicians now append

Accurate coding is important because it determines insurance coverage of cognitive testing, care planning visits, home health, and disease-specific medications. F02.80 in particular tells payers and care teams that a separate underlying neurologic or systemic disease is the driver — which often changes which specialists, medications, and services are appropriate.

What This Means for Your Care

Having F02.80 in your medical record means your healthcare team has documented that your dementia is caused by another disease that is already in your chart. This is most often used by neurologists managing Parkinson's-disease dementia or Huntington's-disease dementia, and by infectious-disease, rehabilitation, or memory-clinic teams managing dementia after HIV, TBI, or other systemic illness.

Because F02.80 is always paired with the underlying-disease code, you'll typically see it on bills alongside codes like G20, G10, B22, or S06 — not by itself. The combination tells your insurance company exactly what's being treated and why specific therapies, imaging, or specialist visits are medically necessary.

If you believe the code doesn't accurately reflect your situation — for example, if the dementia is being attributed to a disease you don't actually have, or if behavioral symptoms have been clearly documented — it's worth raising with your provider's billing department. Coding errors are more common than most people realize.

Understanding the Code Structure

ICD-10-CM codes follow a hierarchical structure. Here is how F02.80 (Dementia in Other Diseases Classified Elsewhere, Without Behavioral Disturbance) fits within the classification:

How This Code Is Used

When your doctor documents dementia caused by another disease, the diagnosis is recorded using ICD-10-CM code F02.80 alongside the code for the underlying disease. This pair appears in your electronic health record (EHR), on insurance claims, and on any medical bills related to the visit.

• Etiology pairing: F02.80 must be billed with the underlying disease code — for example G20 (Parkinson's), G10 (Huntington's), B22 (HIV), or S06 (TBI). The underlying disease is usually listed first.
• Insurance claims: Your provider submits the code pair to justify cognitive evaluations, care planning, and disease-specific treatments tied to the underlying condition.
• Medical records: The combination is stored in your EHR so every provider on your care team understands both that dementia is present and what's driving it.
• Public health: Aggregated F02.x data helps researchers and public health agencies track dementia caused by Parkinson's, Huntington's, HIV, TBI, and other underlying diseases.

Related Diagnosis Codes

Sources

• MedlinePlus: Neurologic Diseases · U.S. National Library of Medicine
• MedlinePlus: Brain and Nervous System · U.S. National Library of Medicine